From: Peter Zijlstra <peterz@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "H.J. Lu" <hjl.tools@gmail.com>,
libc-alpha <libc-alpha@sourceware.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-api <linux-api@vger.kernel.org>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Boqun Feng <boqun.feng@gmail.com>,
Andy Lutomirski <luto@amacapital.net>,
Dave Watson <davejwatson@fb.com>, Paul Turner <pjt@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Russell King <linux@arm.linux.org.uk>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Andi Kleen <andi@firstfloor.org>, Chris Lameter <cl@linux.com>,
Ben Maurer <bmaurer@fb.com>, rostedt <rostedt@goodmis.org>,
Josh Triplett <josh@joshtriplett.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Joel Fernandes <joelaf@google.com>,
Carlos O'Donell <carlos@redhat.com>,
Florian Weimer <fweimer@redhat.com>
Subject: Re: [PATCH for 5.1 0/3] Restartable Sequences updates for 5.1
Date: Wed, 6 Mar 2019 09:21:30 +0100 [thread overview]
Message-ID: <20190306082130.GR32477@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <486623963.509.1551825130539.JavaMail.zimbra@efficios.com>
On Tue, Mar 05, 2019 at 05:32:10PM -0500, Mathieu Desnoyers wrote:
> ----- On Mar 5, 2019, at 4:58 PM, Peter Zijlstra peterz@infradead.org wrote:
>
> > On Tue, Mar 05, 2019 at 03:18:35PM -0500, Mathieu Desnoyers wrote:
> >> * NUMA node ID in TLS
> >>
> >> Having the NUMA node ID available in a TLS variable would allow glibc to
> >> perform interesting NUMA performance improvements within its locking
> >> implementation, so I have a patch adding NUMA node ID support to rseq
> >> as a new rseq system call flag.
> >
> > Details? There's just not much room in the futex word, and futexes
> > themselves are not numa aware.
>
> It was discussed in this libc-alpha mailing list thread:
>
> https://public-inbox.org/libc-alpha/CAMe9rOo7i_-keOooa0D+P_wzatVCdKkTRiFiJ-cxpnvi+eApuQ@mail.gmail.com/
>
> (adding the relevant people in CC)
>
> I'd like to hear in more details on how they intend to design
> NUMA-aware spinlocks within glibc. All I know is that quick
> access to the node ID would help for this.
Userspace spinlocks are a trainwreck anyway. The only case where they
can possibly work is when there's only a single thread on every cpu.
Pretty much any other scenario is fail; see why we have paravirt
spinlocks.
next prev parent reply other threads:[~2019-03-06 8:22 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-05 19:47 Mathieu Desnoyers
2019-03-05 19:47 ` [PATCH for 5.1 1/3] rseq: cleanup: Reflect removal of event counter in comments Mathieu Desnoyers
2019-04-19 10:43 ` [tip:core/rseq] rseq: Clean up comments by reflecting removal of event counter tip-bot for Mathieu Desnoyers
2019-03-05 19:47 ` [PATCH for 5.1 2/3] rseq: cleanup: remove rseq_len from task_struct Mathieu Desnoyers
2019-04-19 10:43 ` [tip:core/rseq] rseq: Remove superfluous " tip-bot for Mathieu Desnoyers
2019-03-05 19:47 ` [PATCH for 5.1 3/3] rseq/selftests: Adapt number of threads to the number of detected cpus Mathieu Desnoyers
2019-04-19 10:38 ` Ingo Molnar
2019-04-19 12:41 ` Mathieu Desnoyers
2019-04-19 12:55 ` Mathieu Desnoyers
2019-04-19 13:42 ` Mathieu Desnoyers
2019-04-19 13:48 ` Mathieu Desnoyers
2019-04-19 14:17 ` shuah
2019-04-19 14:40 ` Mathieu Desnoyers
2019-04-19 18:57 ` shuah
2019-04-19 20:59 ` Mathieu Desnoyers
2019-04-19 21:03 ` shuah
2019-04-19 10:44 ` [tip:core/rseq] " tip-bot for Mathieu Desnoyers
2019-04-19 10:46 ` [tip:core/rseq] rseq/selftests: Adapt number of threads to the number of detected CPUs tip-bot for Mathieu Desnoyers
2019-03-05 20:18 ` [PATCH for 5.1 0/3] Restartable Sequences updates for 5.1 Mathieu Desnoyers
2019-03-05 21:58 ` Peter Zijlstra
2019-03-05 22:32 ` Mathieu Desnoyers
2019-03-06 8:21 ` Peter Zijlstra [this message]
2019-03-06 8:30 ` Peter Zijlstra
2019-03-06 17:00 ` Mathieu Desnoyers
2019-03-05 21:49 ` Peter Zijlstra
2019-04-19 10:41 ` Ingo Molnar
2019-04-19 12:42 ` Mathieu Desnoyers
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